Local oysters blamed for illnesses

By DOUG FRASER

dfraser@capecodonline.com

November 10, 2012 - 2:00 AM

Editor's Note: Because of a reporting error, this story had an incorrect title for William Walton and the wrong location for the college where he works. Walton is an assistant professor at Auburn University in Alabama.

State Department of Public Health testing has shown that eight people became ill this year from eating bacteria-laden oysters, despite brand new regulations that were specifically designed to keep consumers safe.

Until the DPH traced two Vibrio parahaemolyticus cases back to Cape oysters in 2011, the state had never seen that particular gastrointestinal illness caused by oysters harvested in Massachusetts waters. The state's colder waters and climate seemed to discourage the growth of the bacteria, which have a reproductive rate that jumps dramatically with higher water and air temperatures.

One reason for this year's higher number of cases may be increased awareness by the public and medical professionals, leading to more testing and reporting, DPH Associate Commissioner Suzanne Condon wrote in an email to the Times. But her agency also believes warmer water and air temperatures this past summer were primary factors.

The Blue Hill Observatory in Milton reported that every month so far in 2012 has been above the mean temperatures tracked from 1891 to 2010, including the third-warmest April, the sixth-warmest May, the seventh-warmest July and the warmest August on record.

Sea surface temperatures this past year were also the highest ever recorded in the Northeast.

The confirmation of the two 2011 cases prompted the federal government to require the state to create a vibrio management plan. Since vibrio population numbers double every 15 minutes, the primary goal is to inhibit growth by cooling the shellfish. The plan requires that shellfishermen shade their oysters from the sun immediately upon harvesting them and either put them on ice or refrigerate them within five hours. A wholesaler has 10 hours to bring the oysters' internal temperature down below 50 degrees and keep them at that temperature until they reach consumers.

The eight 2012 cases involved oysters from Wellfleet, Orleans, Edgartown, Duxbury, Kingston, Barnstable, and Dennis. The management plan covers nine communities along the eastern shore of Cape Cod Bay from Sandwich to Provincetown, where extreme tides and shallow waters allow give the sun time to bake the oysters on the flats.

The DPH will be evaluating the effectiveness of the vibrio plan in light of this year's cases and could possibly expand coverage to additional towns and/or place limits on the time of year when raw oysters can be harvested and sold, according to Condon. "That would be devastating," said Bob Wallace, a Wellfleet aquaculturist and president of the Massachusetts Aquaculture Association about summer restrictions. "Not prime time to eat them — the fall is the beautiful oyster (season) — but it's when (tourists) are here."

Since the oyster became the king of shellfish in recent years, nearly every town on Cape has licensed aquaculturists growing oysters. The region is tops in the industry in the state. The state Division of Marine Fisheries reports that in 2010, the state's 354 aquaculturists landed nearly 80,000 bushels of oysters with a value of $8.6 million paid to fishermen. "Whatever it takes to have raw shellfish in the summer, we'll do it to make sure (the consumer) is protected," Wallace said. "We don't want them to lose confidence in our industry and we'll do everything we can to ensure they are on the safe side."

This year, the Wellfleet OysterFest — a celebration of the choice mollusk that just wrapped up its 12th annual event last month — made sure that all the oysters were chilled properly and regulations were followed rigorously, organizers said. There were no cases of illness as a result.

While the eight cases in the state seem like a big jump, some scientists and industry officials believe the vibrio plan will work. "There's no question it will solve the problem," said Dale Leavitt, an associate professor and aquaculture specialist for Roger Williams University in Bristol, R.I. Leavitt said there are other links in the chain, such as wholesalers, restaurants and fish markets that also handle the product before it reaches consumers.

"It's going to take a while. All it takes is one person not doing it right, and it all comes back on the growers," he said.

The DPH inspected 39 wholesale seafood distributors this year to check on compliance, according to Condon.

MIT professor and microbiologist Martin Polz was cautious about earlier DPH claims that the recent uptick in vibrio incidents were linked to global warming and climate change. A specialist in vibrio bacteria, Polz agrees that warmer water and air temperatures would positively affect bacterial populations in theory, but he thinks scientists lack conclusive evidence or numbers.

"(There) is a lack of baseline studies," he said. Because gastrointestinal illness from Vibrio p. mimics other sicknesses, such as food poisoning, it may have gone unreported for a while, he said. In that case, it would be hard to know if Vibrio p. was really more prevalent or was simply being reported now because of the publicity.

Former Wellfleet shellfish constable Bill Walton, now an assistant professor at Auburn University in Alabama, agreed that not enough data has been collected to support the climate change theory. He criticized the U.S. Food and Drug Administration, saying the agency even wants to end the sale of raw oysters. "They just seem to take a stance that these shouldn't be sold at all," he said. "As a consumer, I don't want to see that. I love my raw oysters, and I don't see why the world has changed.